Investment Securities - Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Total temporarily impaired securities, Duration Unrealized Loss Position, Less Than Twelve Months, Fair Value	$ 56,232	$ 22,691
Total temporarily impaired securities, Duration of Unrealized Loss Position, Less Than 12 Months, Gross Unrealized Loss	(625)	(80)
Total temporarily impaired securities, Duration of Unrealized Loss Position, Twelve Months or Longer, Fair Value		15,270
Total temporarily impaired securities, Duration of Unrealized Loss Position, Twelve Months or Longer, Gross Unrealized Loss		(127)
Total temporarily impaired securities, Duration of Unrealized Loss Position, Fair Value	56,232	37,961
Total temporarily impaired securities, Duration of Unrealized Loss Position, Unrealized Loss	(625)	(207)
Mortgage-Backed Securities [Member]
Available-for-sale securities, Duration of Unrealized Loss Position, Less than 12 Month, Fair Value	15,859
Available-for-sale Securities, Duration of Unrealized Loss Position, Less than 12 Month, Gross Unrealized Loss	(193)
Available-for-sale securities, Total, Fair Value	15,859
Available-for-sale securities, Total, Unrealized Loss	(193)
Collateralized mortgage obligations [Member]
Available-for-sale securities, Duration of Unrealized Loss Position, Less than 12 Month, Fair Value	15,342	7,448
Available-for-sale Securities, Duration of Unrealized Loss Position, Less than 12 Month, Gross Unrealized Loss	(129)	(29)
Available-for-sale securities, Duration of Unrealized Loss Position, 12 Month or Longer, Fair Value		5,549
Available-for-sale Securities, Duration of Unrealized Loss Position, 12 Month or Longer, Gross Unrealized Loss		(56)
Available-for-sale securities, Total, Fair Value	15,342	12,997
Available-for-sale securities, Total, Unrealized Loss	(129)	(85)
Corporate bonds [Member]
Available-for-sale securities, Duration of Unrealized Loss Position, Less than 12 Month, Fair Value	11,020
Available-for-sale Securities, Duration of Unrealized Loss Position, Less than 12 Month, Gross Unrealized Loss	(206)
Available-for-sale securities, Total, Fair Value	11,020
Available-for-sale securities, Total, Unrealized Loss	(206)
Obligations of state and political subdivisions [Member]
Available-for-sale securities, Duration of Unrealized Loss Position, Less than 12 Month, Fair Value	14,011	1,413
Available-for-sale Securities, Duration of Unrealized Loss Position, Less than 12 Month, Gross Unrealized Loss	(97)	(9)
Available-for-sale securities, Total, Fair Value	14,011	1,413
Available-for-sale securities, Total, Unrealized Loss	$ (97)	(9)
Mortgage-backed - residential [Member]
Available-for-sale securities, Duration of Unrealized Loss Position, Less than 12 Month, Fair Value		13,830
Available-for-sale Securities, Duration of Unrealized Loss Position, Less than 12 Month, Gross Unrealized Loss		(42)
Available-for-sale securities, Duration of Unrealized Loss Position, 12 Month or Longer, Fair Value		9,721
Available-for-sale Securities, Duration of Unrealized Loss Position, 12 Month or Longer, Gross Unrealized Loss		(71)
Available-for-sale securities, Total, Fair Value		23,551
Available-for-sale securities, Total, Unrealized Loss		$ (113)